Incident Investigation

Skill: Incident Investigation

Use this skill to diagnose and resolve production incidents in VoxBento.

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Diagnostic Entry Points

1. Is the portal up?

curl http://localhost:8000/healthz
# Expected: {"ok": true, "server": "fastapi", "mediamtx_ok": true}

2. Is MediaMTX up?

curl http://localhost:9997/v3/paths/list
# Expected: 200 with paths array
docker-compose ps mediamtx
docker-compose logs mediamtx --tail=50

3. Portal logs

docker-compose logs portal --tail=100
# Look for: ERROR, WebSocketDisconnect, DB errors, transcription errors

4. Active booth state (no API for this — check portal logs or DB)

# Check live booth count from admin panel: /admin/
# Or query DB directly:
docker-compose exec portal uv run python -c "
import asyncio
from portal.database import get_session, list_events
async def main():
    async with get_session() as s:
        events = await list_events(s)
        for e in events:
            print(e.slug, e.display_name)
asyncio.run(main())
"

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Common Incident Types

IC-01: Interpreter cannot "Go Live"

Symptoms: "Go Live" button clicked but WHIP fails or spinner never resolves.

Diagnosis:

1. Check browser DevTools Network tab for GET /api/events/{slug}/booths/{lang}/whip-url.
   • 403? → Interpreter is not the active interpreter. Check booth:state WS message.
   • 404? → Booth not in memory. Was the WS booth:join message sent successfully?
2. Check MediaMTX reachability: /healthz → mediamtx_ok.
3. Check MEDIAMTX_WHIP_BASE is browser-reachable (not Docker-internal URL).
4. Check WebSocket connection in DevTools → WS tab.

Fix: If not active interpreter: coordinator must reassign via booth:set-active. If MediaMTX down: docker-compose restart mediamtx.

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IC-02: Listener hears nothing

Symptoms: Listener page loads but WHEP connection shows "disconnected" or audio is silent.

Diagnosis:

1. Check interpreter is "Go Live" — ingest_status == 'connected' in booth state.
2. Check MEDIAMTX_WHIP_BASE in listener page source — must be browser-reachable HTTPS.
3. Browser DevTools → check RTCPeerConnection state in whep-listener.js.
4. Check MediaMTX path: GET http://localhost:9997/v3/paths/get/{event_slug}/{language_code}.
5. Check alwaysAvailable: true on the path — if not set, WHEP fails when no publisher.

Fix: Ensure _ensure_mediamtx_path was called. Manually: PATCH http://mediamtx:9997/v3/config/paths/patch/{path} with {"alwaysAvailable": true}.

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IC-03: WebSocket disconnects repeatedly

Symptoms: Interpreters see connection status flickering; participants disappear and reappear.

Diagnosis:

1. Check portal logs for WebSocketDisconnect.
2. Check browser DevTools WS tab for close code:
   • 4001: Missing/invalid token.
   • 4003: Token scope mismatch.
   • 1006: Abnormal closure (network issue or portal crash).
3. Check for asyncio.Lock deadlock in portal/booth_state.py — portal becomes unresponsive.
4. Check for uncaught exceptions in _handle_* functions (portal logs).

Fix: Restart portal if deadlocked. Fix token scope if 4003 (token was generated for different booth).

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IC-04: Transcription not appearing

Symptoms: Booth is live, transcription enabled, but no captions appear.

Diagnosis:

1. Check active_workers state — portal logs should show worker start: Starting {provider} transcription worker for booth {booth_id}.
2. Check ffmpeg can reach MediaMTX RTSP: docker-compose exec portal ffmpeg -rtsp_transport tcp -i rtsp://mediamtx:8554/{event_slug}/{language_code} -f null - -t 5.
3. Check API key exists and is valid: portal logs for API key missing or Failed to decrypt.
4. Check event.transcription_api_enabled is True for external providers.
5. Check MAX_TOTAL_WORKERS (10) not exceeded: count workers in portal logs.
6. Check booth DB config: db_booth.transcription_enabled, db_booth.transcription_provider, db_booth.transcription_model.

Fix: Restart transcription worker via admin panel → booth detail → transcription settings (re-save). Or call stop_transcription_worker(booth_id) + start_transcription_worker(...) via debug endpoint if available.

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IC-05: Admin login fails

Symptoms: /admin/login with correct password → still shows error.

Diagnosis:

1. Check ADMIN_PASSWORD env var is set and not empty.
2. Check admin_token cookie is being set (DevTools → Application → Cookies).
3. Check JWT secret is consistent (settings.effective_jwt_secret).
4. Alternative: log in as user with is_admin=True — uses /login + user_token cookie.

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IC-06: Database errors

Symptoms: 500 errors on any page involving DB; portal logs show SQLAlchemy errors.

Diagnosis:

1. Check DB URL: DATABASE_URL env var.
2. Check migrations are current: uv run alembic current should show head.
3. If SQLite: check portal-data volume is mounted and has write permission.
4. If PostgreSQL: check connection string and DB server availability.

Fix: Run uv run alembic upgrade head. If corrupt SQLite: restore from backup volume.

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Emergency Commands

# Restart portal only
docker-compose restart portal

# View live logs
docker-compose logs portal -f

# Force-stop all services
docker-compose down

# Full restart
docker-compose up -d

# Apply pending migrations manually
docker-compose exec portal uv run alembic upgrade head

# Check DB migration state
docker-compose exec portal uv run alembic current